Storage system and method of control for storage system

Abstract

The storage system includes a plurality of storage devices and a storage controller. The storage controller stores a data request quantity indicating the data quantity of write data written to the target area in a specific period, and estimates, based on the quantity of request data and relationship information received from storage devices, the estimated data quantity written to the nonvolatile semiconductor memory chips based on the write data written to the target area in the specific period. The storage controller selects a second logical storage area with an estimated data quantity less than an estimated data quantity for the first logical storage area and assigned to a storage device different from a storage device assigned to the first logical storage area, and migrates the first data stored in the first logical storage area to the second logical storage area.

The invention claimed is: 
     
       1. A storage system comprising:
 a plurality of storage devices; and 
 a storage controller coupled to the plurality of storage devices and a host computer, configured to manage a plurality of logical storage areas in a pool volume provided by the plurality of storage devices, 
 wherein each of the plurality of storage devices comprise a plurality of nonvolatile semiconductor memory chips, and a memory controller coupled to each of the plurality of nonvolatile semiconductor memory chips and the storage controller, 
 wherein the storage controller is configured to provide a virtual volume to the host computer and to allocate a logical storage area from the plurality of logical storage areas in the pool volume to the virtual volume in response to a write request from the host computer and transfer write data to at least one of the plurality of storage devices, 
 wherein, each memory controller of the plurality of storage devices is configured to receive the write data from the storage controller, to compress the write data, to write the compressed data to any of the plurality of nonvolatile semiconductor memory chips within the respective storage device, 
 wherein each memory controller of the plurality of storage devices is configured to send relationship information related to an amount of compressed data in the respective storage device to the storage controller, 
 wherein, upon receiving the relationship information from the plurality of memory controllers, the storage controller is configured to determine whether wear level processing on any of the plurality of storage devices is necessary or not based on information of a residual lifetime of each of the plurality of storage devices, 
 wherein the storage controller is configured to specify a first RAID (Redundant Array of Independent Disks) group including at least one storage device among the plurality of storage devices as a short-life RAID group and a second RAID group including at least one storage device that is different from the at least one storage device of the first RAID group among the plurality of storage devices as a long-life RAID group based on the information of the residual lifetime of each of the plurality of storage devices, 
 wherein the storage controller is configured to predict a total write amount of each of the logical storage areas corresponding to the first RAID group and each of the logical storage areas corresponding to the second RAID group based on a compression ratio and a total amount of write data thereof using the relationship information, the compression ratio indicating a ratio of a total amount of compressed data to the total amount of data written for each of the logical storage areas, respectively, 
 wherein the storage controller is configured to specify a first logical storage area corresponding to the first RAID group and a second logical storage area corresponding to the second RAID group based on the total write amount, and 
 wherein, when the total write amount of the first logical storage area is greater than the total write amount of the second logical storage area, the storage controller is configured to perform the wear level processing by migrating data of the first logical storage area to the second RAID group and migrating data of the second logical storage area to the first RAID group. 
 
     
     
       2. The storage system according to  claim 1 ,
 wherein the storage controller is configured to specify a first storage device and a second storage device included in the first RAID group, respectively as a short-life device and a long-life device based on the information of the residual lifetime of each of the plurality of storage devices, 
 wherein the storage controller is configured to predict the total write amount of the first RAID group by using the relationship information, 
 wherein the storage controller is configured to specify a third logical storage area corresponding to the first storage device and a fourth logical storage area corresponding to the second storage device based on the total write amount, and 
 wherein, when the total write amount of the third logical storage area is greater than the total write amount of the fourth logical storage area, the storage controller is configured to perform the wear level processing by migrating data of the third logical storage area to the second storage device and migrating data of the fourth logical storage area to the first storage device. 
 
     
     
       3. The storage system according to  claim 1 ,
 wherein the storage controller is configured to predict the residual lifetime of each of the plurality of storage devices based on a speed of decline of a remaining number of deletions of the respective storage device. 
 
     
     
       4. The storage system according to  claim 1 ,
 wherein each of the plurality of storage devices are configured to send the relationship information including at least one of a total amount of data read from each of the nonvolatile semiconductor memory chips in the respective storage device, a total amount of data written on each of the nonvolatile semiconductor memory chips in the respective storage device, an average compression ratio indicating a ratio of a total amount of compressed data to a total amount of data written for the respective storage device, and a remaining number of deletions of the respective storage device. 
 
     
     
       5. The storage system according to  claim 1 ,
 wherein the plurality of nonvolatile semiconductor memory chips are one of flash memory, MRAM (Magnetoresistive Random Access Memory), ReRAM (Resistance Random Access Memory), FeRAM (Ferroelectric Random Access Memory) and phase change memory. 
 
     
     
       6. The storage system according to  claim 1 ,
 wherein a type of the plurality of storage devices are one of SLC (Single Level Cell), MLC (Multi-Level Cell), and TLC (Triple Level Cell). 
 
     
     
       7. The storage system according to  claim 1 ,
 wherein the plurality of storage devices further comprise a hard disk drive (HDD). 
 
     
     
       8. The storage system according to  claim 1 ,
 wherein the storage controller is configured to determine whether wear level processing on any of the plurality of storage devices is necessary or not at a predetermined time interval. 
 
     
     
       9. The storage system according to  claim 1 ,
 wherein the storage controller is configured to determine whether wear level processing on any of the plurality of storage devices is necessary or not in response to an I/O (input/output) request from the host computer. 
 
     
     
       10. The storage system according to  claim 1 ,
 wherein the storage controller is configured to determine whether wear level processing on any of the plurality of storage devices is necessary or not in response to a specific command from the host computer.